1. Field of the Invention
The present invention relates to an engine control apparatus for a vehicle for temporarily stopping the operation of an engine when, for example, the vehicle is in a halted state while the engine is operating.
This application is based on Japanese Patent Application No. Hei 11-283578 (Unpublished), the contents of which are incorporated herein by reference.
2. Description of the Related Art
Conventionally, a vehicle is known that is provided with an engine stopping apparatus for temporarily stopping an engine that is operating in an idling state such as when waiting for a signal at an intersection, or when a vehicle is stopped in congested traffic or the like, or when a state in which the accelerator pedal is not depressed continues for a predetermined length of time. In this type of vehicle, by stopping the operation of the engine while the vehicle is in an idling state such as when the vehicle is stopped, and operating the engine only when it is necessary for the vehicle to travel, a reduction in the volume of exhaust gas that is expelled and an improvement in the fuel consumption rate is achieved.
However, in congested traffic, for example, when the traveling of the vehicle is series of frequent repeated starts and stops, the stopping and starting of the engine is also frequently repeated. When the engine is started, a shock is generated in the vehicle, and the drawback arises that the frequent repetition of this shock being generated leads to a deterioration in the drivability. Moreover, when the engine is started, the drawback arises that there is an increase in fuel consumption due to the energy used to rotate the starter and the operation of the engine in the poor state of combustion efficiency that exists during startup of the engine. At the same time, the drawback arises that the frequent repetition of the engine starting causes the volume of exhaust gas expelled to increase, compared to when the engine is running while the vehicle is in an idling state.
To counter drawbacks such as these, as is disclosed in, for example, Japanese Unexamined Patent Application, First Publication No. Hei 8-168105, a hybrid vehicle is known which is provided with an engine stopping apparatus for stopping the engine when a congestion determining apparatus determines that the vehicle is in congested traffic and causing a vehicle to travel using only a motor. According to this hybrid vehicle, the frequent repetition of the starting and stopping of the engine can be avoided when the vehicle is in congested traffic, and it possible to achieve a reduction in the amount of exhaust gas expelled and an improvement in the fuel consumption rate by traveling using only the motor.
However, the above hybrid vehicle is a type of hybrid vehicle that is capable of traveling using the output of only the motor when the operation of the engine is stopped. Accordingly, in, for example, a type of hybrid vehicle in which the output of the engine is supplemented by the output of the motor while the vehicle is being started, or in a vehicle that is not provided with a motor (i.e. is not a hybrid vehicle), it is not possible to reduce the repeated starting and stopping of the engine that accompanies the frequent repetition of the starting and stopping of a vehicle in congested traffic or the like. Therefore, the drawback exists that it is not possible to inhibit the deterioration in drivability caused by the shock that is generated in a vehicle when the engine is started, or the increase in the volume of exhaust gas that is expelled.